THURSDAY, Dec. 13 (HealthDay News) -- The prevalence of glaucoma in the United States is 22 percent higher than it was 10 years ago, a new report reveals.

Researchers from Prevent Blindness America and the U.S. National Eye Institute reported that more than 2.7 million Americans aged 40 and older are affected by this eye disease, which can damage the optic nerve and gradually lead to blindness.

Symptoms for glaucoma develop slowly, so the condition is also known as the "sneak thief of sight." The researchers pointed out in a joint news release that more than 50 percent of those who have glaucoma are not even aware of it.

To increase awareness and educate people about glaucoma, Prevent Blindness America joined forces with other leading vision and eye health groups to declare January as National Glaucoma Awareness Month.

Among the people at greatest risk for glaucoma are those who are older and have a family history of the disease. Those who are black, used steroids, are nearsighted or sustained an eye injury are also at much greater risk of developing glaucoma.

"As we begin 2013, we hope that everyone's New Year's resolution will be to make their eye health a priority and schedule an eye exam," Hugh Parry, president and CEO of Prevent Blindness America, said in the news release. "Through early detection and treatment, we can help lessen the effects of glaucoma and other eye diseases on vision."

In a recent issue of the journal Ophthalmology, University of Michigan Medical School researchers reported that statins -- commonly prescribed to lower cholesterol -- may be an effective treatment against a form of early-stage glaucoma, according to background information in the news release.

The U.S. National Library of Medicine has more about glaucoma.